P219A — Bank 1 Air-Fuel Ratio Imbalance
The fuel-trim values across cylinders on bank 1 differ enough that the bank-average air-fuel ratio is biased — a single cylinder is significantly leaner or richer than the rest. Detected by short-term-fuel-trim variance or by the wide-band O2 sensor harmonic monitor.
General code reference. Confirm the definition and diagnostic procedure for your vehicle's year, model and engine. A stored code alone does not identify a failed part.
Affected components
- Fuel injector
- Oxygen sensor
- Intake manifold
Possible causes to check
These are possible checks, not a ranked diagnosis. Follow the vehicle manufacturer's test procedure before replacing parts.
- One injector clogged or leaking
- Vacuum leak at one intake runner
- Low compression on one cylinder
Diagnostic notes
- The malfunction indicator lamp may illuminate
- This code can affect emissions
Related codes
Sources
Check each reference's vehicle and model-year scope. General background links do not establish which fault is most likely on your vehicle.
Diagnostic information is provided for reference only. Confirm the code with a compatible scan tool and follow the vehicle manufacturer's service procedures before replacing components.